Process of roasting ores.



A. B. NEWMAN.

PROCESS OF ROASHNG ORES.

APPLICATION FILED IMR. 23, I916.

1,280,283. Q Patented 001;. 1, 1918.

UNITED STATES PATENT OFFICE.

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ASSIGNOR 'ro METALLURGICAL COMPANY 01 AMERICA, OF NEW YORK, 11. Y., A CORPDBATION 01 NEW JERSEY.

PROCESS OF BOASTING OBES.

Specification of Letters latent.

Patented Oct. 1, 1918.

To all whom it may concern:

Be it known that I, ALBERT B. NEWMAN, a citizen of the United States, residing at Langeloth, county of Washington, State of 5 Pennsylvania, have invented certain new and useful Improvements in Processes of Roasting Ores; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a method of roasting ores, and particularly for roasting zinc sulfid ores and concentrates.

The smelting of zinc oalcines requires that a minimum 0 In order to complete the roasting operation, and eifect what is commonly known as a dead roast, extraneous heat is required, particularly near the end of the roasting operation for the purpose of removing the combined sulfur which is not previously removed.

Where the sulfur dioxid resulting from the roasting operation is to be used later for 26 the manufacture of sulfuric acid it is desirable that a suitable percentage of sulfur dioxid should be present. This consideration precludes the use of the ordinary heating flames directly in contact with the charge 30 because of the dilution of the roaster gases which would thus take place.

According to the present invention, part or all of the heat necessary to be supplied for effecting and completing the dead roast 86 is supplied by the combustion of sulfur either directly in contact with the charge or indirectly, and the sulfur dioxid formed from the combustion of the sulfur is combined with the roaster ases and the sulfur dioxid content thereo thus further increased and embodiment of the invention relates to the direct heating of the ore by the combustion of sulfur in direct contact with the charge, whereby the ore is subjected to the heat of combustion of the burnin sulfur and the heat necessary for the comp etion of the roast partially or entirely supplied in this manner.

The sulfur can be either in the lump form or in the form of powder, or it can be volasulfur be retained in them.

A particularly valuable operation tilized and used as a vapor, together with the air necessary to burn 1t either all at once or in successive stages durin its progress through the furnace. The su fur'may thus be burned progressively in the furnace and the heat thereof made available in a progressive manner. Where the sulfur is used in a solid form it can be supplied at difi'erent ore hearths and burned with the necessary) amount of air so that the resulting roducts of combustion pass intoheating re ation to the ore in the ore hearths and so that the sulfur dioxid formed by the combustion of the sulfur combines with the roaster gases and increases their sulfur dioxid content. V

Where the sulfur is introduced as a vapor it may be all introduced at the lower levels of a multiple hearth furnace and burned all at once or progressively by the introduction of air progressively at different parts of the furnace. The ore in the lower part of the furnace is always hot enough to keep the sulfur volatilized so that the vapor will be carried along with the products of combus tion and subsequently burned by the introduction of further amounts of air. It is thus possible to develop heat from the burning sulfur in the lower levels of a multiple hearth furnace where it is most needed to drive off the last part of the combined sulfur from thecharge. Instead of supplying heat directly to the ore bed by the combustion of the sulfur in the ore hearths, the heat may be to a greater or less extent supplied by the combustion of sulfur in separate heating flues, in a manner similar to that now commonly practised with producer gas as the heating gas in the heating flues; When sulfur is thus used, however, the sulfur dioxid resulting from its combustion is combined with the roaster gases, as by introducin the sulfur dioxid into the ore hearths, an the roaster gases are thus enriched in sulfur dioxid much the same as when the sulfur is burned in direct contact with the ore bed. So also, where heat is supplied by the combustion of the sulfur in the ore hearths, additional or su plemental amounts of heat can be supplied y burning producer s or other fuel sin separate heating fines in much the usua manner without dilution of the roaster a aw uses with the products of combustion of the 9 therein and with a suitable regulable air heating flues. The heat supplied by the inlet 11. This small furnace will usually combustion of the sulfur in the ore hearths be placed near the ore discharge end of the makes it necessary to supply much less heat flue 5.

in the heating flues, with resulting increased In the usual roasting operation, the heat 70 efiiciency of the roasting operation because necessary for completing the roast is furof the large loss of heat incident to the innished by the combustion of producer s direct heatln which must take place throu 'h or like fuel gas in the gas flues 3 and 4 which the wall of the gas flue. Accordingl wh e alternate with the lower ore hearths 5 and the heating with sulfur, eitherdirect or in- 6. According to the present invention,where directly, is to be considered as wit in the the combustion of sulfur suppliesto agreater more general aspects and urposes of the inor less extent the heat necessary for the comvention, the combustion o? the sulfur in the pletion of the roast, the sulfur ma be ore hearths and the direct heating of the burned in the gas flues 3 and i, an the 16 charge in this manner is a particularly valuresulting sulfur dioxid then utilized for able'and important embo lment of the inthe urpose of enriching the roaster ses. vention, whether or not this heatin is supere the sulfur is burned in f e ore plemented by the combustion 0 added hearths and the heat thereby supplied diamounts ofjsulfur or of producer gas or rectly to the charge, less heat isnecessary 80 other fuel gas in separate heating fiues. from the heating fines. In order that the Where the heat is-in part or in whole supheat of the sulfur burned in the ore hearths plied by the combustion of sulfur, either may be more uniform] applied, the air addirectly or indirectly, and the sulfur dioxid mitted through the in et 11 may be insufliresulting from the combustion of the sulfur cient to eifect complete combustion of the 26 is combined with the roaster gases, these sulfur with the resu t that part of the sulfur 9o gases are enriched in sulfur dioxid and made will be vaporized and carried into the flue much richer than es from the usual roast- 5 along with the sulfur dioxid formed. It ing operation, wit the result that a greater has been found that sulfur vapor so carproduction of acid can be effected therefrom ried and burned by the subsequent addition so with the same equipment. of air does not combine with the ore but is In the accompanying drawings, Figure 1 maintained in a va or form. The mixed shows, in transverse vertical section, part of sulfur dioxid and sufur vapor enterin the a multiple hearth roasting furnace adapted roast hearth near the discharge end 0% the for the practice of the invention, and Fig. furnace travels in the opposite direction to 85 2 shows, in longitudinal vertical section, a the travel of the ore, and .air is admitted 10o modified construction of roasting furnace to the ore hearth as required, for the subseadapted for the ractice of the invention. uent and successive combustion of the Fi 1 shows alf of a double multiple c argle and for the completion of the roast. heart roasting furnace, with the 11 per or- The eat of the ore bed is suflicient to keep 40 tionof the. furnace cut away. w' be the sulfur volatilized while the admission understood that the other half is of similar ofair to the ore hearth as required nerconstruction, as is commonin the art, and ates heat which is utilized for eompfiting that aplurality of upper ore hearths will the roastin operation. be provlded. The inner wall which also In supp ying to a greater or less extent 415 forms the inner wall of the other half of the the extraneous heat necessary for a dead 11o furnace, is indicated at 2' At the lower roast by the combustion of sulfur, instead of levels of the furnace are arranged two gas heatlng the ore bed in part directly and in fines 3 and a for the combustion therein of part indirectly by the combustion of sepaproducer gas or ether combustion.,,gas. rate char s of sulfur, a single operation hese flues commumcate with each other by may be e ected by burning the sulfur in one a suitable 'flue (not shown) in the wall 1 of the lower gas fines, either completely or of the furnace similar to the flue 14 of Fi incompletely, and turning the resulting gas 2, and a suitable chimney or line (not shown a while still in a bi hly heated condition into is also rovided for the escape of the an ore hearth. ere the sulfur has been 85 from ,t e upper hearth 4.' The lower ore incompletely burned in the as'flue or lines, hearth 5 is arranged above the gas flue 3 its combustlon can be comp eted by the inso that it will be heated thereby, and the troduction of air after the products of innextore hearth 6 is arranged to be similarly complete combustion have been introduced heated by the gas flue 4, the other upperinto the ore hearth. In this case, the'heat so ore hearths 6 not belng heated otherwise will be partly supplied indirectly and partly 126 than by the heat of the roastinfig operation. directly by the progressive combustion of Opposite the lower hearth and eomthe charge of sulfur first in the gas flue munlcating therewith by a suitable flue 8, and then in the ore hearth. is a small furnace 7 provided withv a bell; The furnace of Fig. 2 is of a similar conhopper 10 for the introduction of the sulfur struction to that of Fig. 1, but instead of having a. separate small furnace at one side of the multiple hearth furnace, one or more sulfur containing ans or receptacles 13 are provided, together with suitable regulable air inlets 11, so that the sulfur will be burned and the resulting heat utilized in the ore hearths. Gas flues 3 and 4 are vided, similar to the flues 3 and 4. of ig. 1, so that the heat generated by the combustion of the sulfur can be supplemented if necessary by indirect heating in the usual manner. T e flues 3 and 4" communicate through a suitable connecting flue 14 in the furnace wall.

The lower ore hearth 5 and the upper ore hearths 6, are similar in construction to the correspondin hearths of Fig. 1, the lower hearths 5* an 6 alternating with the gas flues 3 and 4. Suitably pivoted doors or closures 12 are provided at the ends of the ore fines, for the introduction of rakes, and for the removal of the ore from the lower hearth 5. The pan or rece tacle 13 for the sulfur is arrangedabove t e hearth 5, at its discharge end this receptacle 13 being suitably supporte by the furnace wall. It is shown as projectin a short distance beyond the end wall of t e furnace, but, in practice, it may project from the side wall of the furnace, in a manner not shown, instead of from the end wall. rality of receptacles 13 are used, they can be similarly arranged at such laces along the furnace, or at different leve s, as may be found desirable for supplying the additional heat necessary.

The operation of the; furnace of Fig. 2 is 7 similar to that of the furnace of Fig. 1. The sulfur is burned near the discharge end of the lower ore hearth and the products of combustion, or the mixed sulfur dioxid and sulfur vapors, pass in the opposite direction to the ore along the ore hearth, any sulfur vapors bein successively and subse uently burned to give further increments 0 heat, and-the ore bed being hot enough to keep the sulfur volatilized.

As a result of the combustion'of sulfur-in the furnace, not only is heat supplied to the .ore charge for assisting or completing the final stages of the roast, but the escaping gases are materially enriched in sulfur dioxid, so that the escaping gases are of increased value where they are desired for subsequent conversion into sulfuric acid.

Having thus described my inventiomwhat I claim is:

1. The method of roasting ores and of enriching the roaster gases in sulfur dioxid, which comprises burning sulfur'jn heat interchanging relation with the ore bed and thereby supplying heat thereto for promoting the roastm operation, and combining the products 0 combustion of the sulfur with the roaster gases and thereby enriching Where a pluthe roaster gases in sulfur dioxid; substantially as described.

2. The method of roasting ores and of enriching the roaster gases in sulfur dioxid, which comprises burning sulfur in contact with the ore bed and applying the heat of the combustion directly to the ore bed to remote the roasting operation and also urnin sulfur in heat interchanging relation with the ore bed but not in irect contact therewith, and combining the products of combustion of the sulfur w1th the roaster gases and thereby enriching the roaster gases in sulfur dioxid; substantially as described.

3. The method of roasting riching the roaster gases in which comprises burning pletely, in indirect heating relation to the ore bed and subsequently completing the combustion of the sulfur in direct contact with the ore bed, wherebyheat for promotin the roasting o oration is in art su i plied directly and in. part indirect y by t e combustion of sulfur and whereby the roaster gases are enric ed in sulfur ioxid by the addition thereto of the products of combustion of the sulfur; substantially as described.

4. Themethod of roasting ores and of enriching the roaster gases in sulfur dioxid, which com rises burnin sulfur in direct and thereby apores and of encontact wit the ore be plying heat directly to the ore and enric mg the furnace gases in sulfur dioxid; substantially as described. i

5. The method of roasting ores in a multiple hearth furnace and of enriching the roaster gases in sulfur dioxid, which comprises burning sulfur in direct contact with the ore m the lower levels of the furnace, and thereby suppl ing heat directly to the ore body for comp etin the roasting operation, and enriching t e furnace gases in sulfur -dioxid; substantially as described.

6. The method of roasting ores in a multiple hearth furnace and of enriching the roaster gases in sulfur dioxid, which comprises burning sulfur with, insuflicient air or complete combustion, in direct contact the lower levels of the furnace, and subse uentlyintroducing further amounts of air or completing the combustion of the sulfur in contact with the ore bed, thereby supplying heat to the ore for completing the roasting operation and enriching the sulfur gases'in sulfur dioxid; substantially as described.

7. The method of roasting ores in a multiple hearth furnace and of enriching the roaster gases in sulfur dioxid which comprises burning sulfur in the lower hearth of the furnace near the discharge end, and passing the products of comb nation in the direction opposite to the travel of the ore,

with the ore in sulfur dioxid, sulfur incomthereby supplying heat directly to the ore bed near its discharge from the furnace, and enrichin the furnace gases in sulfur dioxid; substantially as described.

8. The method of roasting ores in a. multiple hearth furnace and of enriching the roaster gases in sulfur dioxid, which comrises burning, in the lower levels of the urnace, sulfur with insuflicient air to cause conplete combustion, and subsequently intro uc1n further amounts of air for cornletm t e combustion thereby supplying eat dlrectl to the ore hed in a progressive manner an enriching the furnace gases in sulfur dioxld; substantially as described.

In testimony whereof I aflix my signature.

ALBERT B. NEWMAN.

It is hereby certified that in Letters Patent No. 1,280,283, granted October 1, 1918, upon the application of Albert B. Newman, of Langeloth, Pennsylvania, for an improvement in Proc of Roasting Ores, errors appeal-in the. printed specification requiring correction as follows: Page 3, line 21, for the-word "flues" read hearth; same page, line 70, claim 2, before the word contact insert the word direct; and that the said Letters Patent should be read with' these corrections therein that the same may conform to the record of the case in the Patent Oflica.

Signed and sealed this 29th day of October, A. D., 1918.

V n F. WHITEHEAD,

Ading Commissioner of Patents.

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